How to use HTML and PHP to implement login and registration interface

With the development of the Internet, various websites and applications have become an indispensable part of people's daily lives. Among them, login and registration are one of the most basic functions. For developers, implementing login and registration interfaces is a basic task. In this article, we will introduce how to use HTML and PHP to implement the login and registration interface.

What are HTML and PHP?

HTML is the standard language used to create web pages. It uses markup to describe the structure and content of a web page. Markup in HTML is usually a combination of tags and attributes, such as

and . PHP is a server-side scripting language that can be used to create dynamic web pages and web applications. PHP is often used in conjunction with databases to generate dynamic content by retrieving data from the database.

HTML implementation of registration form

To create a registration form, we need to use HTML. Form elements in HTML enable users to enter data on a web page and submit it to the server. Below is a simple HTML form that contains some basic input fields such as username, email, and password:

<form action="register.php" method="post">
  <label for="username">用户名:</label>
  <input type="text" id="username" name="username" required>

  <label for="email">电子邮件:</label>
  <input type="email" id="email" name="email" required>

  <label for="password">密码:</label>
  <input type="password" id="password" name="password" required>

  <button type="submit">注册</button>
</form>

In the above code, we have used the form tag to create a form. Among them, the action attribute specifies the address to which the form data should be submitted, and the method attribute specifies the method for submitting the data. In our example, we submit the form to a file called register.php, using the POST method to submit the data.

Next, we use the label tag to mark the input field, and use the input tag to create the input field. Here, we have used a text input field, an email input field, and a password input field. Each input field has a name that can be identified through the name attribute.

Finally, we added a button that when the user clicks on it, the form data will be submitted to the server.

PHP implements registration backend

When the user clicks the "Register" button, the form data will be submitted to the register.php file we specified. Now, we need to process the form data through PHP and store it into the database.

Here is a simple PHP script to create a user and store it into the database:

<?php
//获取表单数据
$username = $_POST[&#39;username&#39;];
$email = $_POST[&#39;email&#39;];
$password = $_POST[&#39;password&#39;];

//连接数据库
$conn = mysqli_connect("localhost", "root", "", "users");

//检查用户名是否唯一
$query = "SELECT * FROM users WHERE username=&#39;$username&#39;";
$result = mysqli_query($conn, $query);
if (mysqli_num_rows($result) > 0) {
  die("用户名已存在！");
}

//插入用户数据到数据库中
$query = "INSERT INTO users (username, email, password) VALUES ('$username', '$email', '$password')";
mysqli_query($conn, $query);

//输出成功信息
echo "注册成功！";
?>

In the above code, we first use $_POST to get the form data. Next, we connect to the MySQL database and execute the SQL query using the mysqli_query function. We also perform some basic error checking, such as checking that usernames are unique.

If the registration is successful, we will output a simple message to the user.

HTML implementation of login form

Now, we have created a registration form and stored it in the database. Next, we need to create a login form.

Here is a simple HTML form with name and password fields:

<form action="login.php" method="post">
  <label for="username">用户名:</label>
  <input type="text" id="username" name="username" required>

  <label for="password">密码:</label>
  <input type="password" id="password" name="password" required>

  <button type="submit">登录</button>
</form>

Unlike the registration form, we only have two fields, username and password. When the user clicks the "Login" button, the form data is submitted to a file called login.php.

PHP Implementation of Login Backend

When a user submits the login form, we need to verify their credentials via PHP so they can be redirected to the correct page. Below is a simple PHP script to check user credentials:

<?php
//获取表单数据
$username = $_POST[&#39;username&#39;];
$password = $_POST[&#39;password&#39;];

//连接数据库
$conn = mysqli_connect("localhost", "root", "", "users");

//检查用户凭据
$query = "SELECT * FROM users WHERE username=&#39;$username&#39; AND password=&#39;$password&#39;";
$result = mysqli_query($conn, $query);
if (mysqli_num_rows($result) == 1) {
  header("Location: dashboard.php");
} else {
  die("无效的用户名或密码！");
}
?>

In the above code, we first use $_POST to get the form data submitted by the user. Next, we connect to the MySQL database and execute the SQL query using the mysqli_query function.

We check if the username and password are correct, if so we will redirect the user to a page called dashboard.php. Otherwise, we will display an error message to the user.

Summary

In this article, we learned how to use HTML and PHP to implement the login and registration interface. We created a registration form to collect user data and store it into a MySQL database. We also created a login form that validates user credentials and redirects them to the correct page. We hope this article helped you better understand how to use HTML and PHP to implement basic login and registration functionality.

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